It is initially hard to see why Lagos has been called the "megacity of the future", with the potential to become the "Singapore of Africa". There's plenty to think about if the Nigerian city of 16 million tightly packed inhabitants is the ultimate expression of modern urban living. Lagos is growing at such an astonishing rate that by 2015 it is predicted to be the third largest city in the world, behind Mumbai and Tokyo, but it is an unlikely model metropolis.

Although the country has vast oil resources, the city's infrastructure is appalling. Three-quarters of Lagos residents live in slums. The rail network manages one train per week. Despite being the world's sixth biggest oil producer, power cuts are a daily occurrence and a national joke. Lagosians have renamed the National Electric Power Authority (NEPA) as Never Expect Power Always.

When I first visited Nigeria, my parents' homeland, a decade ago, I was unprepared for the reality. It was like landing on another planet. Although the city is a nightmare to navigate, the Lagosians are a breed apart. Millions of quick-witted economic migrants have created a city characterised by personal ingenuity and entrepreneurship. Nothing is wasted, everything is a commodity. "Lagos is not a kind of backward situation but an announcement of the future," the architect Rem Koolhaas has said. "What is now fascinating is how, with some level of self-organisation, there is a strange combination of extreme underdevelopment and development."

Will Anderson, the series producer of Welcome to Lagos, a fascinating new three-part documentary, agrees. He believes the way they have addressed the problems of extreme population growth is a lesson for us all, especially now that half the world's population live in cities, including one billion slum dwellers. "I am an anthropologist by background, but rather than looking at marginal and tribal populations, I wanted to look at massive cities. If a Martian came down to Earth, they would report back that we are a species that lives in cities. And in some degrees the people in Lagos are doing it better than we are in the west," he says.

The series looks at life on the Olusosun rubbish dump, the workplace and home to more than 1,000 scavengers who sift the garbage looking for recyclable material. This is a vibrant, self-policing community living next to a mosque, a barber's shop and three cinemas. The film-makersalso take us to Makoka lagoon where 300,000 people live on water and in squatter camps on the beach. It is soon clear that most Lagos residents will do anything to earn a few dollars a day, from back-breaking labour to sharp business deals, because there is no welfare state to provide a safety net.

But among Lagosians, who tend to combine relentless entrepreneurial flair with the belief that God will provide, there is little time for self-pity, a fact reflected in the series. "We did not want the people to come across as victims because that is not how they see themselves," says Anderson. "They are normal people doing what they have to do to survive. They encounter the same obstactles as the rest of us, but it's just that they do so in extreme circumstances."

Welcome to Lagos will be shown on BBC 2 at 9pm on 15, 22 and 29 April

Voices from the margins

ERIC OBUH

Eric, 28, works as a scavenger on the Olusosun landfill site, the largest dump site in Lagos, and has recorded his first album "Send Them Come".

"They call me Slender, Vocal Slender, that's my music name. Because I'm very lean in the face, and because I'm always singing my songs. I have so many songs I still want to record, good songs that I've written, but no one has heard. Songs about divine love, peace and unity in Nigeria, and others which praise all the girls.

"The film crew have made me a website. MySpace. It's not easy to get a website on your own. I know about 200 singers in Ajegunle where I live, but only two or three have websites. Ajegunle is the biggest ghetto in Lagos. It's where all the biggest Nigerian stars come from, people like Daddy Showkey, Baba Fryo, Mighty Mouse, African China, B'Clean, and Nico Gravity. Every night there's a party going on somewhere, people playing music on the street corners, or setting up sound systems to dance to.

"One day I'm going to be more famous than Craig David. Then I'll have enough money to be able to spend all day on my music, instead of working here on the dump. A lot of people who know me, my friends, and my family, they don't know I work in the dump. They believe I just do music. And I want to keep it that way, so I will have respect. It's not that the dump is bad, because the money I get from it keeps my body and soul together, and helps me make my music."

MOHAMMED ADAMU

Mohammed, 30, is a cattle dealer at the Oluwainshola Cattle Market and Slaughter Yard on the outskirts of Lagos.

"I am planning to marry presently, some time soon. I think it is the right time. I'm 30 now, and I have sent a message to my family letting them know I am ready. They will arrange everything. Her name is Aysha. I have met her three times already, during my trips home to my village in the north. She is good, I like her, there is love and understanding and I don't doubt her at all.

My family are very happy with me. To have only one wife is OK by me. I have seen the disadvantages people have with more than one wife. I want to get a house in Lagos, and to live with her here. She has never left her village. But I cannot be going up and down to the north all the time – the expenses would be too much.

"I am waiting to know the exact day of the wedding. I will have to provide property for her, and decorative things, two or three bags of clothes. The bags will be filled with everything concerning women's dresses, including the shoes. The only thing they have asked me for is jewellery. The whole thing will cost around 150,000 naira (£600). I know I can reach that amount.

"When the day comes, me and my friends will go to the north, and my wife's family will cook. W e'll gather for prayers, and then I'll take my wife to the house to celebrate the wedding. The next day I'll bring her back to Lagos, and continue selling cows in the market."

ESTHER OGUNLEKE

Esther, 24, lives in a house built on Kuramo Beach, a tiny spit of sand attached to Victoria Island, Lagos's most upmarket neighbourhood.

"I've just finished reading The Girl with the Dragon Tattoo. One of the film crew left me her copy when she said goodbye. I thought it was beautiful and exciting, and I want to read the next one in the trilogy, but I haven't been able to find a copy anywhere. I pray to God that he will provide one. I love to read so much.

"This is me, outside my house on Kuramo beach. It's a small stretch of sand attached to Victoria Island, one of the most upmarket neighbourhoods in Lagos. Everyone thinks only drug addicts, armed robbers and prostitutes live here, but they never come to find out the truth. I've lived on the beach for almost eight years. There's about 1,000 of us here. Shopkeepers, motorbike taxi drivers, even businessmen who work in banks. My best friend, Lati, runs a cinema house next to where I live. We watch Nollywood movies, and all the Chelsea matches. I could never be friends with anyone who supports Manchester United. They are the Red Devils. They are devilish. Maybe they are using their devilish substance to win all the major trophies they have been winning. I hate them. Their nickname is very bad. Up Chelsea! Blues for life!

"My house cost about £60 to build. You have to buy the wood and tarpaulins, and then pay a tax to the local chairman. I like to keep it very clean. When I was arguing with my husband, we had a big fight about who was going to get the house. I wasn't going to let him leave me homeless, with nowhere to go.

"In this picture, I'm getting dressed up for church. I'm a member of the Redeemed Christian Church of God. On the first Friday of every month they hold a 'miracle service'. Sometimes there's more than a million people praying together; it's quite fantastic, and then I know God will never give up on me ..."

JOSEPH ORJI

Joseph, 39, is a scrap trader at the Olusosun landfill site, and lives 10 minutes walk away with his wife and two young daughters.

"My business depends on the dollar. When the dollar goes down, the price goes down. When the dollar is up, the price goes up. The only difference between me and someone who works in the stock market is the suit and the tie, and the fine shoes. I've been working on the dump for 12 years. I'm a buyer. I buy from the scavengers, and sell to the reprocessing factories. Aluminium, zinc, copper wire, rubber slippers – all this is what I buy.

"All these big rich people, they don't like to conserve things. They throw everything away, even if there's nothing wrong with it! My house is full of the things I've found on the dump. Toasted-sandwich makers. Field glasses. Even my daughter's teddy.

"My older daughter, Peace, will be four in May. One day, she's going to be the future Miss World. My wife Elizabeth and I believe she's going to be great in life. That's what we pray for. I don't mind what she does or how she does it – she'll make her own life.

"I'm not ashamed to work in the dump. All my neighbours know that's where I work.I don't rob. I don't steal. I'm an honest person. What is important is love for your family. That's what drives you to walk that extra mile. If there was a dump that was stinkier than this one, where I could earn more, then I'd go there to work, just to make sure my family enjoys life.

The government are not interested in our recycling business. They don't look at us as human beings. They just look at us as if we are miscreants. Vagabonds. But they don't know that we are the tyres of the nation. We move the nation forward."